From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45899) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WDhaV-0006KQ-6g for qemu-devel@nongnu.org; Wed, 12 Feb 2014 16:43:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WDhaQ-00027i-6j for qemu-devel@nongnu.org; Wed, 12 Feb 2014 16:43:23 -0500 Received: from paradis.irqsave.net ([62.212.105.220]:49826) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WDhaP-00027B-Ne for qemu-devel@nongnu.org; Wed, 12 Feb 2014 16:43:18 -0500 Date: Wed, 12 Feb 2014 22:43:15 +0100 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20140212214315.GA10146@irqsave.net> References: <1392068957-14184-1-git-send-email-benoit.canet@irqsave.net> <1392068957-14184-2-git-send-email-benoit.canet@irqsave.net> <20140211081217.GB12675@T430.nay.redhat.com> <20140212194918.GC4225@irqsave.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20140212194918.GC4225@irqsave.net> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [FIX V2] block: Fix device snapshots broken by the block filter snapshots patchset. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?iso-8859-1?Q?Beno=EEt?= Canet Cc: kwolf@redhat.com, Fam Zheng , qemu-devel@nongnu.org, jcody@redhat.com, armbru@redhat.com, mreitz@redhat.com, stefanha@redhat.com The Wednesday 12 Feb 2014 =E0 20:49:18 (+0100), Beno=EEt Canet wrote : > The Tuesday 11 Feb 2014 =E0 16:12:17 (+0800), Fam Zheng wrote : > > On Mon, 02/10 22:49, Beno=EEt Canet wrote: > > > Take into account the fact that a block filter like quorum will be = in bs->file > > > while a regular block driver device is really on the top level. > > >=20 > > > Signed-off-by: Benoit Canet > > > --- > > > block.c | 14 ++++++++------ > > > 1 file changed, 8 insertions(+), 6 deletions(-) > > >=20 > > > diff --git a/block.c b/block.c > > > index 07ac50a..d04f535 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -5400,14 +5400,16 @@ bool bdrv_is_first_non_filter(BlockDriverSt= ate *candidate) > > > =20 > > > /* walk down the bs forest recursively */ > > > QTAILQ_FOREACH(bs, &bdrv_states, device_list) { > > > - bool perm; > > > - > > > - if (!bs->file) { > > > - continue; > > > + bool perm =3D false; > > > + > > > + if (bs->file && > > > + bs->file->drv && > > > + bs->file->drv->authorizations[BS_IS_A_FILTER]) { > > > + perm =3D bdrv_recurse_is_first_non_filter(bs->file, ca= ndidate); > > > + } else if (bs =3D=3D candidate) { > > > + perm =3D true; > > > } > > > =20 > > > - perm =3D bdrv_recurse_is_first_non_filter(bs->file, candid= ate); > > > - > > > /* candidate is the first non filter */ > > > if (perm) { > > > return true; > >=20 > > With this change, if the top level driver has ->file, its implementat= ion of > > .bdrv_recurse_is_first_non_filter() is skipped and bs->file is the st= art point. > >=20 > > So we have an implication that single child block drivers (that has -= >file) > > doesn't need to, and shouldn't implement this operation, as commentte= d above > > bdrv_generic_is_first_non_filter. > >=20 > > Tested that this patch fixes the external snapshot problem, but didn'= t test > > the "quorum as bs->file case". > >=20 > > Thanks, > >=20 > > Reviewed-by: Fam Zheng >=20 > After extensive testing of all type of quorum instanciations and snapsh= ots I > discovered that we are not done yet with this issue. >=20 > When instantiating quorum from the command line the quorum driver is in > bs->file->drv. > When using QMP's blockdev_add at once or by using references the quorum= driver > is in bs->drv. >=20 > As a result this patch work in half the cases: regular file and command= line > quorum but not when quorum is instantiated via QMP. >=20 > I don't understand why the block layer have this irregular behavior reg= arding > quorum instantiation. >=20 > What would be the best way to fix this ? I have a pending resping of this patch which tests for the two cases as a workaround. Should I post it ? Best regards Beno=EEt >=20 > Best regards >=20 > Beno=EEt >=20